JP7029412B2 - Microflow limiter assembly and its manufacturing method - Google Patents

Description

(Mutual reference of related applications)
This application claims the priority benefit of US Provisional Application No. 62 / 298,168 filed February 22, 2016, the entire contents of which US provisional application is hereby referenced. It is used inside.

The present invention generally relates to the field of flow limiters, and more specifically to micro flow limiters useful in medical applications.

Microflow limiters are commonly used in the medical field in conjunction with infusion pump systems to regulate the flow of medicines and other fluids to a patient. Microflow limiters are typically capable of adjusting fluid flow within the range of less than 500 ml / hour, but can adjust higher flow rates as needed. The typical pressure at which the injection pump system operates is less than about 60 kPa.

The difficulties to consider with respect to existing microflow limiters are recognized in the prior art. Specifically, with respect to maintaining flow through the limiter over time, prior art microflow limiters are very susceptible to sudden stops due to the presence of fine particles and bubbles in the fluid. Conceivable. A small amount of fluid flowing through the limiter and the minimum operating pressure of the infusion pump moves or otherwise overcomes the particles, or breaks the bubbles and allows the fluid to continue flowing through the limiter. It is believed to provide inadequate pressure. To address this issue, selective prior art microflow limiters have been specifically designed to form multiple meandering paths for fluids, such paths that break bubbles. It is designed to allow fine particles to be circulated by a fluid.

However, prior art flow limiters are expensive to manufacture due to the use of very small fluid paths. Some existing flow limiters are manufactured using costly processing and post-processing steps. In addition, existing flow limiters suffer from a decrease in flow rate over time due to micro-leakage within the flow limiter.

Unexpectedly, in the light of the prior art, we have discovered that the triboelectric effect generated by a fluid flowing through a microfluidic limiter affects the flow of the fluid through the limiter over time. did. By managing the triboelectric effects of fluid and microflow limiters, microflow limiters can function consistently as intended over time. In addition, the unique configuration of the fluid path in the present invention allows for better control of the triboelectric effect, while at the same time simplifying the manufacturing process and reducing manufacturing costs. Therefore, the present invention allows the management of very small amounts of fluid flowing over time without significant interference from the triboelectric effect within the microfluidic limiter configuration, which is more cost effective. Allows manufacturing in style.

The present invention is directed to a medical fluid microfluidic assembly including an assembly fluid inlet and an assembly fluid outlet. A mandrel with an outer surface is positioned within the cavity of the housing such that at least a portion of the outer surface of the mandrel is substantially parallel to at least a portion of the inner surface of the cavity. At least one protrusion extends from either the inner surface of the cavity or the outer surface of the mandrel, and each protrusion abuts on either the outer surface of the mandrel or the inner surface of the cavity and is a sealed fluid channel. To form. The sealed fluid channel may include a channel inlet located close to the assembly fluid inlet and a channel outlet located close to the assembly fluid outlet.

The sealed fluid channel has a length and an average width, and in certain embodiments, the length of the channel may be 10 times greater than the average width of the sealed fluid channel. The average width of the sealed fluid channel may be at least 50 microns and, in some embodiments, wider than 50 microns. The sealed fluid channel may have a constant width along at least a portion of the length of the sealed fluid channel, or may have a width that varies along at least a portion of the length of the channel. May be good. In certain embodiments, the width of the sealed fluid channel may be increased along at least a portion of the length of the channel so that the sealed fluid channel is widest in close proximity to the channel outlet.

The outer surface of the mandrel may be variously shaped and may have a conical shape such that the sealed fluid channels may extend around the outer surface of the mandrel in a spiral pattern.

In certain embodiments, the portion of the outer surface of the mandrel may be planar. At least a portion of the inner surface of the cavity may be configured to be substantially parallel to the planar portion of the outer surface of the mandrel. At least two parts of the outer surface of the mandrel are planar and both parts are substantially parallel to at least part of the inner surface of the cavity, in the configuration the protrusions have at least two sealed fluid channels. It may be positioned on each plane surface of either the mandrel or the cavity so that it is formed.

The protrusion may extend from either the planar portion of the outer surface of the mandrel or the inner surface of the cavity. In some embodiments, the protrusions may extend from the outer surface of the mandrel and the inner surface of the cavity.

The sealed fluid channel, in some embodiments, has an average height, which is the average distance between the outer surface of the mandrel and the inner surface of the cavity of the housing. The sealed fluid channel also has an average width, and in some embodiments, the average width of the sealed fluid channel is at least equal to, for example, at least 3 times, at least the average height of the sealed fluid channel. 5 times, or at least 10 times. In some configurations, the average height of the sealed fluid channel may be equal to or greater than about 5 microns and less than about 500 microns. At least one of the surfaces forming the sealed fluid channel is less than about 10%, for example less than about 5%, of the average height of the sealed fluid channel, ideally possible. It may have an average surface roughness that is as smooth as possible.

The protrusion may include a first surface and a second surface, where the first and second surfaces are in contact with either the outer surface of the mandrel or the inner surface of the cavity and are sealed fluid channels. Form a vertex. In some configurations, the vertices may be formed as radii, which in some configurations can be greater than or equal to 0.001 microns.

The sealed fluid channel may be formed from a material that, at least in part, exhibits a substantially neutral triboelectric charge when in contact with saline or glucose solution. To achieve this, the sealed fluid channel may be formed from polycarbonate, at least in part. The portion of the sealed fluid channel may also be formed from polysulfone, acrylic, PVC, nylon, polyethylene, polypropylene polymer, or a combination of these materials and polycarbonate.

Medical fluid microfluidic assembly has a flow rate above about 0.01 ml / hour, and in some configurations, at a flow rate of less than about 500 ml / hour, a sealed fluid channel allows fluid to flow through the assembly fluid outlet. May be configured to enable.

According to another aspect of the invention, a method for manufacturing a medical fluid microfluidic assembly is provided. The method may include forming a medical fluid microfluidic assembly housing with cavities and forming a mandrel with an outer surface. In addition, prior to solidification of at least one of the medical fluid microfluidic assembly enclosure or mandrel material, the mandrel extends from either the inner surface of the cavity or the outer surface of the mandrel, at least one portion. Positioned within the cavity of the housing of the medical fluid microfluidic assembly such that the solidified protrusion abuts on either the outer surface of the mandrel or the inner surface of the cavity to form a sealed fluid channel. May be done. The partially solidified material has a larger deformation capacity, thereby compensating for geometric and manufacturing variations, forming a more perfect seal between the microfluidic assembly housing and the mandrel, micro. Reduces the nature of the leak. After the step of positioning the mandrel within the cavity of the medical fluid microfluidic assembly enclosure, the mandrel and / or the medical fluid microfluidic assembly enclosure is solidified through either time, temperature, chemistry, or other means. In one embodiment, the medical fluid microfluidic assembly is assembled when all components are fully solidified except for the medical fluid microfluidic assembly housing, which is partially solidified during assembly. In another embodiment, only the mandrel is partially solidified during the assembly of the medical fluid microfluidic assembly.

In another embodiment, the method comprises the step of achieving the desired flow rate through a microfluidic assembly. For example, the method involves loading a medical fluid microfluidic assembly enclosure with a cavity into a fixture and applying a curable adhesive to the interior surface of the cavity between the cavity and the strut. It may include a step of applying on a part of. The method further comprises monitoring the air flow rate of the pressurized gas or the pressure difference between the inlet and outlet, eg, the vacuum at the outlet, and the pressurized gas from the channel inlet to the channel outlet through a sealed fluid channel. It may include a step of passing and a step of adjusting the pressure contact of the strut to the mandrel based on the monitored air flow rate. The curable adhesive may then be cured when the measured air flow rate reaches the target air flow rate.
The present specification provides, for example, the following.
(Item 1)
Medical fluid microfluidic assembly
Assembly fluid inlet and assembly fluid outlet,
A mandrel having an outer surface, wherein the mandrel is positioned within the cavity of the housing such that at least a portion of the outer surface of the mandrel is substantially parallel to at least a portion of the inner surface of the cavity.
At least one protrusion extending from either the inner surface of the cavity or the outer surface of the mandrel, each protrusion abutting on either the outer surface of the mandrel or the inner surface of the cavity. Forming a sealed fluid channel, the sealed fluid channel has a protrusion having a channel inlet located close to the assembly fluid inlet and a channel outlet located close to the assembly fluid outlet.
A medical fluid microfluidic assembly.
(Item 2)
The sealed fluid channel has a length and an average width, the length of the channel is 10 times greater than the average width of the sealed fluid channel, and the average width of the sealed fluid channel is. The medical fluid microfluidic assembly according to item 1, which is at least 50 microns.
(Item 3)
The medical fluid microscopic according to item 2, wherein at least a part of the outer surface of the mandrel has a conical shape, and the sealed fluid channel extends around the outer surface of the mandrel in a spiral pattern. Fluid assembly.
(Item 4)
The medical fluid microfluidic assembly of item 3, wherein the sealed fluid channel has a constant width along at least a portion of the length of the sealed fluid channel.
(Item 5)
The medical fluid microfluidic assembly according to item 3, wherein the sealed fluid channel has a width that varies along at least a portion of the length of the sealed fluid channel.
(Item 6)
In item 5, the sealed fluid channel has a width that increases along at least a portion of the length of the channel so that the sealed fluid channel is widest in close proximity to the channel outlet. The described medical fluid microfluidic assembly.
(Item 7)
The medical fluid microfluidity according to item 1, wherein at least a portion of the outer surface of the mandrel is planar and at least a portion of the inner surface of the cavity is substantially parallel to the planar portion of the outer surface of the mandrel. assembly.
(Item 8)
7. The medical fluid microfluidic assembly of item 7, wherein the at least one protrusion extends from either a planar portion of the outer surface of the mandrel or the inner surface of the cavity.
(Item 9)
At least two parts of the outer surface of the mandrel are planar and both parts are substantially parallel to the inner surface of the cavity so that the protrusions form at least two sealed fluid channels. The medical fluid microfluidic assembly according to item 8, which is located on each plane surface of either the mandrel or the cavity.
(Item 10)
The sealed fluid channel further includes an average height, which is the average distance between the outer surface of the mandrel and the inner surface of the cavity of the housing, and the average width of the sealed fluid channel is the above. The medical fluid microfluidic assembly according to item 2, which is at least 3 times the average height of the sealed fluid channel.
(Item 11)
The medical fluid microfluidic assembly according to item 10, wherein the sealed fluid channel has an average height equal to or greater than about 5 microns and less than about 500 microns.
(Item 12)
The medical use according to item 10, wherein at least one of the surfaces forming the sealed fluid channel has an average surface roughness of less than about 10% of the average height of the sealed fluid channel. Fluid microfluidic assembly.
(Item 13)
The medical fluid micrometer according to item 1, wherein at least one of the surfaces forming the sealed fluid channel has an average surface roughness greater than about 0.012 microns and less than about 5 microns. Fluid assembly.
(Item 14)
The protrusion further comprises a first surface and a second surface, the first and second surfaces contacting either the outer surface of the mandrel or the inner surface of the cavity and the seal. The medical fluid microfluidic assembly according to item 1, wherein the fluid channel is formed, the apex is formed.
(Item 15)
The medical fluid microfluidic assembly according to item 14, wherein the apex is formed as a radius greater than or equal to 0.001 micron.
(Item 16)
The medical fluid microfluidic assembly of item 1, wherein the sealed fluid channel is formed, at least in part, from a material that exhibits substantially neutral triboelectricity when in contact with saline or glucose solution.
(Item 17)
The medical fluid microfluidic assembly according to item 1, wherein the sealed fluid channel is at least partially formed of polycarbonate.
(Item 18)
The medical fluid of item 1, wherein the sealed fluid channel is at least partially formed from polycarbonate, polysulfone, acrylic polymer, PVC (polyvinyl chloride), nylon, polyethylene, polypropylene, or a combination thereof. Microfluid assembly.
(Item 19)
Item 1. The sealed fluid channel is configured to allow fluid to flow through the assembly fluid outlet at a flow rate of greater than about 0.01 ml / hour and less than about 500 ml / hour. Medical fluid microflow assembly.
(Item 20)
The medical fluid microfluidic assembly according to item 1, wherein the sealed fluid channel is configured to allow fluid to flow through the assembly fluid outlet at a flow rate greater than about 0.01 ml / hour. ..
(Item 21)
A method for manufacturing a medical fluid microfluidic assembly, wherein the above method is used.
Steps to form a medical fluid microfluidic assembly housing with cavities,
The steps to form a mandrel with an outer surface,
Prior to solidification of at least one of the medical fluid microfluidic assembly housing or mandrel, at least one partially solidified extending from either the inner surface of the cavity or the outer surface of the mandrel. Position the mandrel within the cavity of the medical fluid microfluidic assembly housing so that the protrusion abuts on either the outer surface of the mandrel or the inner surface of the cavity to form a sealed fluid channel. A step, wherein the sealed fluid channel has a channel inlet and a channel outlet, thereby reducing sagging in the medical fluid microfluidic assembly.
After the step of positioning the mandrel in the cavity of the medical fluid microfluidic assembly housing, a step of solidifying at least one of the mandrel or the medical fluid microfluidic assembly housing.
Including, how.
(Item 22)
Steps to form a strut with an assembly fluid outlet,
Prior to solidification of at least one of the medical fluid microfluidic assembly housing, the mandrel, or the struts, the struts are placed in the housing so that the assembly fluid outlet of the struts communicates with the channel outlet. With the step of pressing against the above mandrel in the cavity of
21. The method of item 21, further comprising.
(Item 23)
The method according to item 22, wherein the step of pressing the strut against the mandrel in the cavity of the housing utilizes a motorized linear actuator.
(Item 24)
With the step of forming a connector with an opening extending through it,
With the step of fixing the connector to the medical fluid microfluidic assembly housing so that at least a portion of the column is positioned within the opening of the connector.
22. The method of item 22.
(Item 25)
A step of applying an adhesive to a part of the inner surface of the cavity of the housing between the inner surface of the cavity and the strut,
Steps to monitor the air flow rate of pressurized gas and
A step of passing the pressurized gas from the channel inlet to the channel outlet through the sealed fluid channel,
The step of adjusting the pressure contact of the column with respect to the mandrel based on the monitored air flow rate, and
When the monitored air flow rate reaches the target air flow rate, the step of curing the adhesive
21. The method of item 21, further comprising.
(Item 26)
21. The method of item 21, further comprising solidifying the partially solidified protrusion extending from either the inner surface of the cavity or the outer surface of the mandrel.

FIG. 1A is a perspective view of an injection pump system utilizing an embodiment of a microfluidic assembly according to aspects of the present invention. FIG. 1B is another perspective view of an injection pump system utilizing an embodiment of a microfluidic assembly according to another aspect of the invention. FIG. 2A is a perspective exploded view of the microfluidic assembly of FIG. 1A. FIG. 2B is a perspective exploded view of another embodiment of the microfluidic assembly. FIG. 3A is a perspective view of an embodiment of a microfluidic assembly according to the present invention. FIG. 3B is a side view of an embodiment of the microfluidic assembly depicted in FIG. 3A. FIG. 4A is a cross-sectional view of the microfluidic assembly depicted in FIG. 3B obtained along lines AA. FIG. 4B is a cross-sectional view of an embodiment of a microfluidic assembly. FIG. 4C is a cross-sectional view of the assembled microfluidic assembly depicted in FIG. 2B. FIG. 5 is a side view of an embodiment of a fluid dowel useful in the present invention. FIG. 6 is an end view of the fluid dowel depicted in FIG. FIG. 7 is a side view of an embodiment of a housing useful in the present invention. FIG. 8 is a cross-sectional view of the housing depicted in FIG. 7 obtained along lines BB. FIG. 9 is an enlarged view of the circled portion of the housing depicted in FIG. FIG. 10 is an enlarged view of the circled portion of the housing depicted in FIG. FIG. 11 is an enlarged view of the circled portion of the microfluidic assembly depicted in FIG. 4A. FIG. 12A is a side view of the embodiment of the mandrel. FIG. 12B is a side view of another embodiment of the mandrel. FIG. 12C is a side view of yet another embodiment of the mandrel. FIG. 13A is a perspective view of yet another embodiment of the mandrel. FIG. 13B is a top view of an alternative embodiment of the mandrel. FIG. 13C is a cross-sectional view of the mandrel depicted in FIG. 13B. FIG. 13D is a perspective view of different embodiments of the mandrel. FIG. 13E is a cross-sectional view of another embodiment of the mandrel. FIG. 14 is a partial cross-sectional view of the mandrel and the housing. FIG. 15 is a cross-sectional view of an embodiment of a microfluidic assembly located in the reservoir of a portable infusion pump. FIG. 16 is a flow chart illustrating an exemplary method of manufacturing a microfluidic assembly according to aspects of the invention. FIG. 17 is a flow chart illustrating an exemplary method of achieving a desired flow rate through a microfluidic assembly according to aspects of the invention. FIG. 18 is a graph illustrating the advantages of manufacturing microfluidic assemblies with partially solidified "undried" components.

The present invention will be described herein with reference to one or more embodiments illustrated in the drawings. It should be understood that the embodiments for carrying out the invention are provided as an explanation of the invention and are not intended as a limitation of the invention. For example, the features illustrated and described as part of one embodiment may be used on another embodiment and still provide further embodiments. The invention is intended to include these and other modifications and variations to the embodiments described herein.

FIG. 1A illustrates a portable infusion pump system 110 for delivery of fluid to a patient. The portable infusion pump system 110 typically includes a reservoir 112, a reservoir support, and tubes 114 through which fluid from the reservoir 112 flows. The reservoir 112 may also function as a pump, typically a rubber or elastomer bladder, which is designed to apply constant pressure to the contents of the pump during the infusion process. Typical pressures in a portable infusion pump system can range from about 20 kPa to about 60 kPa.

As shown in FIGS. 1A and 1B, the fluid inlet of the microfluidic limiter 10 may be connected to the medical tubing 114 and receive the fluid from the reservoir 112. The fluid passes through the microfluidic limiter 10 and exits into the needle assembly 113 through the fluid outlet of the microfluidic limiter 10 and flows into the needle assembly 113 or flows to the patient or in FIG. 1B. As shown, it exits into the medical tube 116 and flows to the patient.

The microfluidic assembly 10 has a number of available to form medical tubing, luer locking connectors, and fluid paths at its assembly fluid inlet 28 and assembly fluid outlet 26 (both shown in FIG. 3A). It may be configured to engage and retain various articles, such as any other of the mechanism.

The microfluidic limiter assembly 10 may be utilized to limit the flow of fluid to the patient. The microfluidic limiter assembly 10 may be connected to the reservoir 112 via a medical tube 114 or may be connected to the patient using various mechanisms. For example, as shown in FIG. 1A, the microfluidic limiter assembly 10 is configured to engage the medical tube 114 at one end and the established intravenous site of the patient at the other end. Needle assembly 113 may be connected. In other configurations, as shown in FIG. 1B, the microfluidic limiter assembly 10 may be connected to a medical tube 116, which may have a needle assembly 113 connected to the other end. Optionally, multiple microfluidic limiter assemblies may be used in the fluid path between the reservoir 112 and the patient. For example, in FIG. 1B, the fluid is needled from the reservoir 112 into the medical tubing 114 through the microfluidic limiter assembly 10 and into the medical tubing 116 through the second microfluidic limiter assembly. Flow into assembly 113 and to the patient. Instead of the needle assembly 113, other articles may be utilized, including catheters, luer locking joints, or other special joints.

With reference to FIGS. 2A-4B, medical fluid microfluidic assemblies are shown in these figures. The microfluidic assembly 10 includes an assembly fluid inlet 28 and an assembly fluid outlet 26, which allows fluid entering the assembly fluid inlet 28 to pass through the microfluidic assembly 10 and from the microfluidic assembly 10 through the assembly fluid outlet 26. Connected fluidly to leave. The assembly fluid inlet 28 may, in some embodiments, be located within the housing 22 as shown in FIGS. 4A and 4B. The assembly fluid outlet 26 may, in some embodiments, be located within the stanchion 14 as shown in FIGS. 4A and 4B.

FIG. 2A is an exploded view of an embodiment of the microfluidic assembly 10, which includes a housing 22, a mandrel 20, a dowel 18, a seal 16, a strut 14, and a connector 12. Other embodiments of the microfluidic assembly 10 may be configured such that selected elements such as the mandrel 20 and dowels 18 are formed as a single component. For example, the housing 22 and the connector 12 may be formed as a single component, which may also include a seal 16. The stanchion 14, seal 16, dowel 18, and mandrel 20 may also be formed as a single component. In certain embodiments, the selected parts may be omitted for ease of manufacture.

As seen in FIG. 2A, the mandrel 20 is located within the housing 22 and may include a cavity 70, an end 68, and an outer surface 66. The dowel 18 may be useful in embodiments where the mandrel 20 is formed with the central cavity 70. The body 50 of the dowel 18 may be positioned within the cavity 70 of the mandrel 20 and may be useful for providing support to the mandrel 20. The main body 50 of the dowel 18 may occupy only a part of the central cavity 70.

The stanchion 14 is configured to move the dowel 18 and the mandrel 20 into the cavity 80 in the housing 22. In an optional embodiment, the stanchions 14 and dowels 18 may be formed as a single element. Depending on the suitability for a particular manufacturing process, the stanchions 14, seals 16, dowels 18, and connectors 12 may be formed as one or more elements. For example, the stanchions 14 and dowels 18 may be formed as a single element. In other embodiments, the stanchions 14, dowels 18, and connectors 12 may be formed as a single element. The stanchions 14, mandrel 20, and dowels 18 may be formed as a single element or may be spliced together via an adhesive, ultrasonic weld, screw, or snap fitting feature.

The seal 16 may be formed as part of the stanchion 14 or may be formed separately and positioned between the stanchion 14 and the internal surface 86 of the housing 22. For example, the seal 16 may be positioned within the detent 46 of the strut 14 so that the seal 16 comes into contact with the outer surface of the strut 14 and the inner surface 86 of the housing 22. The seal 16 ensures that the fluid is transmitted only through the passage 42 and prevents the fluid from bypassing the restricted flow channel that measures the proper flow of the fluid through the microfluidic assembly 10. Works for. The seal 16 also helps prevent the adhesive used to join the stanchions 14 to the internal surface 86 of the housing 22 from interfering with the flow of fluid through the microfluidic limiter assembly 10. The seal 16 may be formed from any of a variety of materials, including silicone, rubber, or other suitable materials. In certain embodiments, the stanchion 14 and seal 16 may be formed as a single element, and the seal 16 may be co-molded with the stanchion 14, mandrel 20, dowel 18, or housing 22. The stanchion 14, the seal 16, and the connector 12 may also be formed as a single element.

FIG. 2B is an exploded view of another embodiment of the microfluidic assembly, which includes a housing 22, a mandrel 20, a seal 16, a strut 14, and a connector 12. As seen in FIG. 2B, the strut 14 may include a threaded feature 15. In addition, the housing 22 may include a spiral groove and the strut 14 may include a spike-like portion. The seal 16 may be overcast molded.

FIG. 3A shows an embodiment of the microfluidic assembly 10 in the assembled state and depicts an assembly fluid outlet 26 located within a strut 14. The assembly fluid inlet 28, shown in FIG. 4, is located within the housing 22. FIG. 3B illustrates a side view of the assembled microfluidic assembly 10 of FIG. 3A.

As shown in FIGS. 3A and 3B, the outer surface 30 of the connector 12 may include features such as recesses 32 to improve its ease of use. The recess 32 or other gripping features may be formed in a variety of ways, for example, ribs, knurling, or just rough surface textures.

The connector 12 includes an opening 34 that may extend through the connector 12. Threads 36 may be formed within the internal surface 35 of the opening 34 to allow the fluid source to be releasably engaged with the microfluidic assembly 10. Luer locking fittings and snap fitting connections are particularly well suited for use in conjunction with the connector 12.

As shown in FIGS. 4A and 4B, the housing 22 further includes an end 78 that may be positioned adjacent to the connector 12. The connector 12 may include, in selected embodiments, a recessed surface 38 configured to engage the housing 22 and a shoulder 40. As shown in FIG. 4B, the stanchion 14 and the connector 12 may be designed such that the connector 12 snaps into the stanchion 14 or is otherwise mechanically connected.

The end 78 of the housing 22 adjacent to the exit portion 74 abuts on the recessed surface 38 of the connector 12. The shoulder portion 40 of the connector 12 may extend around at least a part of the outlet portion 74 of the housing 22. In certain embodiments, the housing 22 and the connector 12 may both be clamped together or secured by an adhesive or other splicing process such as ultrasonic welding, retention features, or fasteners. As depicted in the microfluidic assembly of FIG. 4B, the housing 22 may simply abut on the connector 12 and be anchored in place by other elements of the microfluidic assembly 10. In certain embodiments, the housing 22 and the connector 12 may be integrally formed as a single element.

The embodiment of the microfluidic assembly depicted in FIG. 4B shows that the mandrel 20 is located in the cavity 80 of the housing 22 and that the mandrel 20 does not have a cavity and is in contact with the stanchion 14. The mandrel 20 and the stanchion 14 may be formed as a single element or may be spliced together by an adhesive, a retention mechanism, ultrasonic welding, and an equivalent.

As shown in FIGS. 5 and 6, the dowel 18 may further include a disc 52 having a circumference 64 and a lower surface 54 that may be positioned adjacent to the end 68 of the mandrel 20. The disc 52 may include at least one boss 58 on it, and in some embodiments, an upper surface 56 on which multiple bosses 58 may be located. The upper surface 60 of each boss 58 may come into contact with the column 14.

4A-4C and 7-10 depict a housing 22 useful in the present invention. The housing 22 includes an outlet portion 74 and an inlet portion 76. In the embodiments depicted in FIGS. 7 and 8, the assembly fluid inlet 28 is positioned in close proximity to the inlet portion 76 of the housing 22. The outer surface 73 of the housing 22 may be variously formed to meet the specific needs of the user. The exterior of the housing may be configured to allow the user to easily and firmly grip the housing 22. Information about the properties of the microfluidic assembly 10 may be engraved on the housing 22.

As shown in FIG. 8, the housing 22 includes an internal surface 86 that forms the cavity 80. The cavity 80 may have an area such as an inlet portion 84 and a transition portion 82. The internal surface 86 of the housing 22 may be variously molded and may have several portions that are flat, curved, conical, or other shapes.

As shown in FIG. 4A, in the selective embodiment, the assembly fluid inlet 28 may be positioned adjacent to the cavity 80, which may have an inlet portion 84. The fluid enters the microfluidic assembly 10 through the assembly fluid inlet 28 in the housing 22.

As best shown in FIG. 11, the outer surface 66 of the mandrel 20 is positioned in close proximity to the inner surface 86 of the cavity 80 of the housing 22.

The strut 14, as shown in FIGS. 2A and 4A-4C, has an inlet end 48. The passage 42 in the strut 14 extends from the inlet end 48 to the assembly fluid outlet 26. The inlet end 48 of the stanchion 14 is positioned in contact with the boss 58 or the mandrel 20 of the dowel 18. As seen in FIGS. 2A and 4A, the stanchion 14 may also include a collar 44 that extends outward from the stanchion 14 close to the inlet end 48 and surrounds at least a portion thereof. Depending on the assembly of the stanchions 14 into the housing 22, the collar 44 may have a gap between the collar 44 and the inner surface 86 of the cavity 80 or between the outer surface of the stanchions 14 and the inner surface 86 of the cavity 80. It may be configured to be formed in either. Adhesives may be used to attach the stanchions 14 to the housing 22 and, in selective embodiments, to the mandrel 20. An permeable type adhesive may be used to fill the gap and secure the components together. Such an adhesive may be applied after the stanchion 14 has been positioned within the housing 22.

The gap between the stanchions 14 and the housing 22 may range from about 0.01 mm to about 1.25 mm and, in selected embodiments, about 0.075 mm.

As seen in FIG. 4C, which is a cross-sectional view of the microfluidic assembly depicted in FIG. 2B in the assembled configuration, the strut 14 may include threaded features 15. The threaded feature 15 may engage at least a portion of the internal surface 86 of the housing 22.

Referring to FIG. 8-13B, at least one protrusion 90 is located on either the inner surface 86 of the cavity 80 of the housing 22 or the outer surface 66 of the mandrel 20. FIG. 8 shows a protrusion 90 located on the inner surface 86, which is the area where the mandrel 20 will be located. The protrusion 90 may extend along the substantial length of the housing 22, and in some embodiments may extend beyond the length of the mandrel 20. This allows flexibility in the process by which the microfluidic assembly 10 is constructed by allowing wider variation in the positioning of the mandrel 20 within the housing 22.

9 and 10 show the embodiment of the protrusion 90 in more detail. The protrusion 90 may be formed as a lamp having a width W and a height H at its highest end. The protrusion 90 may include a first surface 92 and a second surface 94, the first and second surfaces 92, 94 forming vertices 96, as shown in FIG. The protrusion 90 may extend along the inner surface 86 or outer surface 66 of the mandrel 20 over a length sufficient to form at least two complete windings around the circumference of the inner surface 86. good.

FIG. 11 shows a protrusion 90 that abuts on the outer surface 66 of the mandrel 20. As seen therein, the sealed fluid channel 100 is formed between the inner surface 86, the outer surface 66, and the protrusion 90. In the embodiment shown in FIG. 8-11, the sealed fluid channel 100 forms a spiral path for the fluid through the microfluidic limiter assembly 10.

In certain embodiments, the protrusion 90 has a length that extends substantially in a continuous spiral over at least a portion of the inner surface 86 or the outer surface 66. The protrusion 90 may be positioned on such a surface in different ways. For example, the distance between the continuous winding of the protrusions 90 or the pitch of the protrusions 90 may be increased or decreased with respect to the direction of flow of the fluid through the assembly. The pitch of the protrusions 90 may also be uniform or non-uniform along the length of the surface. For example, as illustrated in FIG. 12A, the protrusions 90 are positioned on the outer surface 66 of the mandrel 20, and the pitch of the protrusions 90 decreases in the flow direction. The pitch of the protrusions 90 shown in FIG. 12B increases with respect to the fluid flow direction. FIG. 12C illustrates the non-uniform positioning of the protrusion 90 onto the surface 66. FIGS. 12A-12C are merely exemplary, the protrusions 90 may form more windings around the surface 66.

Many configurations of the protrusion 90 are suitable for use in the present invention, including protrusions having a cross-sectional shape that is triangular, elliptical, orthogonal, or circular. However, at vertex 96 (shown in FIG. 10), during assembly of the mandrel 20 and housing 22, the compressive load will be focused, allowing a controlled deformation of the small total area at vertex 96. It is desirable to select the area. This allows the local stress at the apex 96 to exceed the plastic limit of the material on which the protrusion 90 is formed.

The local deformation of the protrusion 90 is preferably configured to avoid the generation of hoop stress in the housing 22 sufficient to cause cracks. The materials selected for the protrusion 90, the housing 22, and the mandrel 20 will affect the robustness of the microfluidic assembly 10 to cracks. In addition, the angle of the outer surface 66 of the mandrel 20 will affect the resistance of the housing 22 to cracks. In some embodiments, an angle of 7 degrees (14 degree comprehension) allows the mandrel 20 to self-lock without producing excessive hoop stress. Angles of 5-9 degrees (10-18 degrees comprehension angle) are also suitable for use in the present invention.

As described above, the sealed fluid passage 100 of the present invention is formed by the inner surface 86 of the housing 22 and the outer surface 66 of the mandrel 20. The particular configuration of the mandrel 20 and the housing 22 may achieve a diversely structured and sealed fluid path 100. In some embodiments, the internal surface 86 of the housing 22 provides a tapered conical recess in which the mandrel 20 is positioned. The outer surface 66 of the mandrel 20 may be formed as a corresponding tapered conical surface from which a protrusion 90 extends.

As shown in FIGS. 13A-13D, the outer surface 66 of the mandrel 20 may include, at least in part, the planar surface of the wedge. These types of mandrel 20 would be suitable for use in the housing 22, which has at least a portion of its inner surface 86 formed as an angled planar surface.

FIG. 13A shows a mandrel 20 formed as a wedge on which a protrusion 90 is located. The inner surface 86 of the housing 22 is such that when the mandrel 20 is inserted into the housing 22, at least a part of the inner surface 86 becomes substantially parallel to and separated from the outer surface 66 of the mandrel 20. Should be molded.

As shown in FIG. 13A, the protrusion 90 is positioned on the mandrel 20 such that when the wedge-shaped mandrel 20 is engaged with the housing 22, two sealed fluid channels 100 are generated. .. One, two, or more sealed fluid channels 100 may be included within the microfluidic assembly 10.

The sealed fluid channel 100 may surround the mandrel 20 or be located on a single side of the mandrel 20. 13A-13D depict a mandrel 20 having at least one planar surface on which a protrusion 90 is formed. The protrusion 90 of FIG. 13A forms two sealed fluid channels 100 that move the fluid back and forth across a single surface of the mandrel 20. The embodiments in FIGS. 13B and 13C position the protrusion 90 on a single surface of the mandrel 20, however, the sealed channel 100 is formed as a vortex and the fluid exits the vortex through the opening 71 and the channel 72. do. FIG. 13D depicts a mandrel 20 as a wedge with protrusions 90 located on two surfaces of the mandrel 20. In some embodiments, the protrusion 90 may be positioned on a mandrel 20 having a rectangular cross section, as shown in FIG. 13E. The wedge 21 may be used to move the mandrel 20 to an appropriate position within the housing 22.

The protrusion 90 may be specifically configured for the particular surface on which it is located. For example, as shown in FIG. 8, the protrusion 90 extending along the inner surface 86 of the cavity 80 extends beyond the length of the mandrel 20 when the mandrel 20 is positioned within the housing 22. You may.

The height of the protrusion 90 is preferably uniform.

In some embodiments, the angles of the inner surface 86 of the housing 22 and the outer surface 66 of the mandrel 20 should be selected so that their top portions also present a tapered conical morphology. Allows the mandrel 20 and the housing 22 to be in a self-locking state. To achieve this, can the taper angle be essentially a self-tightening angle for the particular material utilized to form the protrusion 90 on the mandrel 20 and the housing 22? Or it can be slightly below that. For example, the polycarbonate material has a self-tightening angle of about 15 degrees (30 degree comprehension angle). Utilization of such self-locking features allows a wider range of joining processes to be successfully utilized on the microfluidic assembly 10.

Referring to FIG. 14, the fluid in the cavity 80 passes over the protrusion 90 into the sealed fluid channel 100. The configuration of the mandrel 20 and the housing 22 creates a rectangular inlet for the sealed fluid housing 100. Bubbles in the fluid are likely to come into contact with the edges of the rectangular inlet, as illustrated in FIG. The rectangular inlet of the sealed fluid channel 100 can generate a pressure point, which assists in breaking bubbles such as bubbles 106 contained in the fluid.

The configuration of the sealed fluid channel 100 may encounter laminar flow, which may be useful in maintaining the air / water correlation of flow. The fluid flows through the sealed fluid channel 100 and exits in close proximity to the dowel 18. The seal 16 prevents fluid from exiting the housing 22 except through a passage 42 terminated at the assembly outlet 26. Different configurations of the microflow limiter 10 may also include alternative configurations of the columns 14, the connector 12, and the housing 22.

The sealed fluid channel 100 may, in certain embodiments, have a height of more than about 5 microns and less than about 500 microns and a width of more than about 50 microns and less than about 6,000 microns. The height of the sealed fluid channel 100 may be adjusted by the distance the mandrel 20 is inserted into the housing 22. The fluid flowing through the sealed fluid channel 100 may be selected by making a sealed fluid channel 100 with a specific height H, a specific width W, and a specific length L.

Referring to FIG. 15, the microflow limiter assembly may be formed as an integral component of a portable infusion pump. As shown in FIG. 15, the portable infusion pump 1500 may include a microflow limiter assembly 10'that is at least partially incorporated into the reservoir 112'. The components of the micro-flow limiter assembly 10'may be constructed, for example, in the same manner as the micro-flow limiter assembly 10 of FIG. 2A. For example, the mandrel 20'of FIG. 15 corresponds to the mandrel 20 of FIG. 2A, the seal 16'of FIG. 15 corresponds to the seal 16 of FIG. handle. The stanchion 14'may be positioned within the tube socket. The microflow limiter assembly 10'has a mandrel 20', a seal 16', and a strut 14'positioned within the housing 22' to form a sealed fluid channel, as described above. , Includes housing 22'.

The microflow limiter assembly 10'may include a filling inlet 1502 having a fluid channel extending through it from the filling inlet 1502 to the one-way valve 1504 located in the reservoir 112'. The reservoir 112'may receive the fluid through the filling inlet 1502 and the one-way valve 1504 may prevent the fluid from exiting the reservoir 112' through the filling inlet 1502. The one-way valve 1504 may be any one-way valve known in the art. The microfluidic limiter assembly 10'may include an inlet 1508, which allows fluid from the reservoir 112' to flow through the microfluidic limiter assembly 10'and finally through the medical tubing 116'. Make it possible. In addition, the reservoir 112'may be secured onto the microfluidic limiter assembly 10' via a ring clamp 1506.

In one embodiment of the micro-flow limiter 10, either a static or impulse load is applied to the strut 14, which limits the air flow while moving the mandrel 20 to a suitable position within the housing 22. It may be assembled in an instrument configured to flow from the assembly inlet 28 to the assembly outlet 26 through the vessel 10.

The pressure applied to the stanchions 14 is used to regulate the flow rate flowing through the microfluidic assembly 10. A flow rate of 500 ml / hour to 0.5 ml / hour is achievable, and in certain embodiments, a flow rate of 0.5 ml / hour to 0.01 ml / hour may be achieved. As pressure is applied to the stanchion 14, the outlet end of the stanchion 14 presses against the surface 60 of the boss 58 located on the dowel 18. The lower surface 54 of the dowel 18 further moves the mandrel 20 into the cavity 80. In selected embodiments, the overhangs 90 may be compressed or deformed to reduce the height H of the sealed fluid channel 100.

The flow rate of the sealed fluid channel 100 and the adjustment of the seal depend on the deformation of the protrusion 90 and the surface on which it is deformed. The configuration of the apex 96 of the protrusion 90 may vary widely, however, smaller areas of the apex 96 may have local stresses formed at the apex 96, which may exceed the plastic limits of the material on which the protrusion is formed. Will make it possible.

In order to allow deformation of the protrusion 90 located on the inner surface 86 of the housing 22, the material selected to form the protrusion 90 is softer than the material used to form the mandrel 20. May be. In contrast, the material used to form the mandrel 20 may be selected to be softer than the material used to form the protrusion 90. In this situation, the mandrel 20 will deform around the protrusion 90. The same material may be used to form both the protrusion 90 and the mandrel 20 and both may be deformed to allow the formation of an airtight seal.

As air flows through the microfluidic assembly 10, air flow is measured, and in many embodiments of the invention, the configuration of the sealed fluid channel 100 provides an air / water correlation, which of the device. It will allow accurate calibration. Any potential leakage through the seal 16 or other parts of the device will occur after the fluid has passed through the sealed fluid channel 100, allowing accurate flow measurements to be achieved.

An adhesive such as a UV curable adhesive may be applied between the columns 14 and the housing 22 prior to insertion into the housing 22 and application of a load to the columns 14. The desired flow rate through the microfluidic assembly 10 is achieved before the adhesive is cured. The adhesive may also be applied after the mandrel 20 has been inserted into the correct position within the housing 22 and the desired flow rate has been achieved, but impact or other handling is due to the position of the strut 14 or mandrel 22. , The flow rate can be modified. Once the adhesive has hardened, the dimensions of the sealed fluid channel 100 are fixed.

Injection molding is an economical and accurate method in which a portion of the microflow limiter 10 can be manufactured. During the injection molding process, the injection mold wears and the protrusion 90 can increase in height due to this change. However, the method of assembly adapts to this potential change in the manufacturing process and allows the microfluidic limiter 10 to be assembled in the same fashion to a preset flow rate. The method of assembly also adapts to variations in the manufacture of components.

Here, with reference to FIG. 16, a method 1600 for manufacturing the microfluidic limiter assembly 10 is described. In step 1602, the medical fluid microfluidic assembly housing 22 with the cavity 80 is formed from a material, eg plastic, using a machine, eg, an injection molding machine. After injection molding, the plastics are uncured in that they are partially solidified. For polycarbonate, the solidification / curing process takes 3-5 days. Prior to that, the uncured plastic is slightly soft and is referred to as "undried" and is, for example, partially solidified. Other "undried" plastics that can be solidified by application of energy, such as heat (thermosolidability), UV, etc., may be used. In addition, solidification of "undried" plastics may be prevented or delayed, for example, by refrigeration, freezing, or chemicals. Thus, the "undried" plastic may subsequently be solidified / cured by reversing the anti-caking, eg, by applying heat or another chemical.

Similarly, in steps 1604, 1606, and 1608, a mandrel 20 with an outer surface 66, a strut 14 with an assembly fluid outlet 26, and a connector 12 with an opening 34 extending through it are machined, eg, injection molded. Using a machine, it is formed from a material, for example plastic. In step 1610, the mandrel 20 extends from either the inner surface 86 of the cavity 80 or the outer surface 66 of the mandrel 20, as described above, at least one partially solidified uncured protrusion. The 90 is positioned within the cavity 80 of the housing 22 such that it abuts on either the outer surface 66 of the mandrel 20 or the inner surface 86 of the cavity 80 to form a sealed fluid channel. The sealed fluid channel includes a channel inlet located close to the fluid inlet 28 and a channel outlet located close to the fluid outlet 26, whereby the flow rate over time in the medical fluid microfluidic assembly. Reduce the decrease.

Unexpectedly, we used partially solidified uncured plastic to form the protrusion 90, which improved the consistency of the flow rate over time, with the protrusion and the mandrel 20. It has been determined to prevent or minimize flow rate reduction ("sagging") over time that may result from microleakage between the outer surface 66 or the smooth surface of either the inner surface 86 of the housing 22. ..

We have found that a slightly lower hardness allows the swirl features, eg, protrusions 90, to deform to a point sufficient to form more and impermeable seals. In one embodiment, the protrusion 90 on the inner surface 86 of the housing 22 is "undried", while the outer surface 66 of the mandrel 20 is solidified plastic. In another embodiment, the outer surface 66 of the mandrel 20 is "undried", while the protrusion 90 on the inner surface 86 of the housing 22 is solidified plastic. In yet another embodiment, both protrusions 90 on the outer surface 66 of the mandrel 20 and the inner surface 86 of the housing 22 are "undried". In contrast to the industrial standard of waiting for the plastic to cure prior to assembly, we believe that assembling the components of a medical fluid microfluidic assembly prior to solidification reduces the rate of change in flow rate. I found. For example, the partially solidified components that are assembled together can be cured to fill the unwanted microgap between the components resulting from the manufacturing process.

The seal between the housing 22 and the mandrel 20 is important to provide a consistent flow rate due to the sagging phenomenon described above. Other methods for sealing may include, for example, lasers, photons, solvents, vibrations, ultrasonic waves and the like.

In step 1612, the stanchion 14 is pressed against the mandrel 20 in the cavity 80 of the housing 22 so that the assembly fluid outlet 26 of the stanchion 14 communicates with the channel outlet. In step 1614, the connector 12 is secured to the housing 22 so that at least a portion of the stanchion 14 is positioned within the opening 34 of the connector 12. As described above, the connector 12 may be designed such that the connector 12 is snap-fitted onto the stanchion 14 or otherwise mechanically connected.

In conventional practice, most plastic parts are mass-produced by external distributors and stored prior to assembly, thus providing a reasonable amount of time for the plastic to solidify. However, according to aspects of the invention, the uncured components are relatively rapid (eg, less than 12 hours after each component is formed, less than 8 hours after each component is formed, 6 hours after each component is formed). Assembled to less than), thereby reducing sagging. In step 1616, the housing 22, the mandrel 20, the stanchions 14, and the connector 12 are solidified / cured. Curing time may be a function of the particular plastic. For example, the curing time / solidification time of polycarbonate is 3 to 5 days, for example, 36 to 60 hours.

Steps 1610-1616 describe assembling a plurality of partially solidified components to form a microfluidic limiter assembly, but not all components need to be partially solidified. Please understand that. For example, in one embodiment, the microfluidic limiter assembly is assembled when all components are completely solidified except for the housing 22, which is partially solidified during assembly. In another embodiment, only the mandrel is partially solidified during the assembly of the medical fluid microfluidic assembly. After assembly, the housing 22 is allowed to solidify / cure, thereby reducing sagging.

Here, with reference to FIG. 17, exemplary methods of achieving the desired flow rate through the microfluidic assembly 10 are described. Method 1700 may be performed using a microfluidic assembly machine. For example, the microfluidic assembly machine may include controllers such as computers, motorized linear actuators, fixtures, flow meters such as mass flow meters, and UV light. In step 1702, the micro-flow limiter assembly housing 22 is loaded into the fixture of the micro-flow assembly machine.

In step 1704, a curable adhesive, such as a UV curable epoxy, is applied to the inner surface 86 of the housing 22. The adhesive may be applied to a portion of the inner surface 86 of the housing 22 in the cavity between the inner surface 86 and the stanchions 14. Adhesives, such as Dymax1160-m-sv01, may contain fluorescent elements for easier visual or mechanical visual inspection. In one embodiment, the adhesive may be applied to the internal surface 86 of the housing 22 before the housing 22 is loaded into the fixture. In yet another embodiment, the adhesive may be applied to the internal surface 86 of the housing 22 after the components of the micro-flow limiter assembly 10 have been cured and the micro-flow limiter assembly 10 has been fixed.

In step 1706, the mandrel 20 has at least one partially solidified protrusion 90 extending from either the inner surface 86 of the cavity 80 or the outer surface 66 of the mandrel 20, as described above. It is positioned within the cavity 80 of the housing 22 so as to abut on either the outer surface 66 of the mandrel 20 or the inner surface 86 of the cavity 80 to form a sealed fluid channel.

In step 1708, the stanchion 14 is pressure-welded to the mandrel 20 in the cavity 80 of the housing 22, for example, a motor capable of slowly but consistently increasing the compressive force of a hydraulic or rotary actuator or the like. The microflow limiter assembly 10 is compressed by a formal linear actuator or any mechanism well known in the art. As described above, using partially solidified plastic, the protrusions 90 can be more deformed to produce a good seal and prevent sagging.

In step 1710, the air flow rate of the pressurized gas, eg, air or _N2 , is monitored via a flow meter prior to passing through the fluid channel sealed in step 1712. In one embodiment, the differential pressure across the sealed fluid channel may be monitored via a flow meter. The flow meter provides a near-instantaneous value of air flow through a sealed fluid channel. Since the air flow rate correlates with the fluid flow rate, the micro flow limiter assembly 10 adjusts the compression of the micro flow limiter assembly 10 in step 1714 until the air flow rate monitored in step 1708 reaches the target air flow rate. This can be adjusted to the desired fluid flow rate.

Once the target air flow rate, and thus the desired fluid flow rate through the microflow limiter assembly 10, is achieved, in step 1716 the adhesive is cured, for example by activating UV light, which adheres. The agent is cured to fix the location of the stanchions 14, and thus the location of the mandrel 20 in the housing 22. As will be appreciated by those skilled in the art, the adhesive may be cured by any curing means well known in the art.

With reference to FIG. 18, a graph illustrating the advantages of manufacturing the microfluidic assembly 10 with uncured "undried" components is illustrated. As described above, the manufacture of the microfluidic limiter assembly 10 using components formed from partially solidified uncured plastic provides improved consistency of flow over time. It results in reducing or further preventing sagging in the medical fluid microfluidic assembly 10. FIG. 18 illustrates the results of the experiments performed, thereby indicating the flow rate of air through the microfluidic assembly manufactured using the solidified plastic component indicated by line 1802 by line 1804. It was compared to the flow rate of air through a microfluidic assembly manufactured using uncured "undried" plastic components.

As shown in FIG. 18 and as seen in Table 1 below, the air flow through the microfluidic assembly manufactured using uncured "undried" plastic components is consistent over a 40 hour period. It was (about 3 mL / hour). In contrast, as shown in FIG. 18 and as seen in Table 2 below, the air flow rate through the microfluidic assembly manufactured with solidified plastic components is over a period of 40 hours. Decreased (from 2.27 ml / hour to 1.83 mL / hour).

Unexpectedly, in the light of the prior art, the sudden stop phenomenon is not due to bubbles and fine particles, but rather to triboelectric charges generated by the fluid flowing through the microfluidic limiter. I found. Specifically, we found that the flow of saline through the limiter was not interrupted despite the increased potential for particulate clogging, and medical grade water for infusion was consistent over time. We paid attention to the fact that it exhibited a slower flow rate.

Triboelectric charging is a type of contact charging in which certain materials come into contact with each other and exchange electrons. This effect is amplified as the fluids and materials of the microfluidic limiter assembly slide into contact. This electrically charges the material. The polarity and intensity of the charges produced will vary based on the particular material and the surface roughness of those materials and the distance between the surfaces. By managing the effects of triboelectric charges on the combined fluids and micro-flow limiters, the micro-flow limiters can function consistently as intended over time.

The control of triboelectricity generated by the fluid flowing through the sealed fluid passage 100 is the surface roughness of each of the optimal materials on which the mandrel 20 and housing 22 are formed and the surface forming the sealed fluid channel 100. Careful consideration of the configuration will be required. The material may be selected to match a particular medical fluid. For example, the polycarbonate material may be selected for medical saline or glucose solutions, including additive agents.

The surface roughness used herein is the average surface roughness _Ra , which is calculated as follows by characterizing the surface based on the absolute value of the vertical deviation of the roughness profile from the average line. In the equation, y is the height of deviation from the average line.

In certain embodiments selected for a particular application, the inner surface 86 and the outer surface 66 preferably have a surface roughness of about 0.012 microns to about 5 microns. The surface roughness is preferably less than 10%, for example, less than 5% of the height H of the sealed fluid channel 100. Not all surfaces forming the sealed fluid channel 100 may come into contact with the fluid, but in some embodiments all surfaces forming the sealed fluid channel 100 traverse the surface. It is preferred to have a surface roughness that significantly reduces the effects of arbitrary triboelectricity from the flowing fluid. The roughness of the surfaces 66 and 86 may also differ from each other.

Although many materials may be used to form the microfluidic limiter assembly 10, including metal and glass, polymers are generally economical and adaptable materials for use. A wide range of polymers are suitable for use in the present invention and should be selected to accommodate the particular use of microfluidic assemblies. Polymers such as polycarbonate, polysulfone, and acrylic plastics, such as poly (methyl methacrylate (PMMA), PVC (polyvinyl chloride), nylon, polyethylene, and polypropylene, are used to form part of the microfluidic limiter assembly. In particular, medical grade polycarbonate may be used for many potential uses of microfluidic assemblies. In some embodiments, the selected polymer is a microfluidic limiter assembly. For a particular application, the material may be matched to a particular fluid to reduce the effects of frictional charging. In some embodiments, the material selected should exhibit a minimal amount of creep.

It will be appreciated by those skilled in the art that various modifications and variations may be made to the features of the medical fluid microfluidic limiters described herein without departing from the scope and spirit of the invention. Should be. The present invention is intended to include all such variations.

Claims (7)

A method of forming an impermeablely sealed fluid channel in a microfluidic assembly, said microfluidic assembly.
With a microfluidic assembly housing with an internal surface,
A mandrel having an outer surface, the mandrel adjacent to the microfluidic assembly housing such that at least a portion of the outer surface of the mandrel is parallel to at least a portion of the inner surface of the microfluidic assembly housing. Mandrel and
The method comprises at least one protrusion extending from either the inner surface of the microfluidic assembly housing or the outer surface of the mandrel.
By contacting the at least one protrusion with either the outer surface of the mandrel or the inner surface of the microfluidic assembly housing to form the impermeablely sealed fluid channel. The impermeablely sealed fluid channel has a channel inlet and a channel outlet.
Bonding the at least one protrusion to either the inner surface of the microfluidic assembly housing or the outer surface of the mandrel by laser, photon, solvent, vibration, or ultrasonic bonding. Including methods. A sealing method for manufacturing microfluidic assemblies, wherein the method is
Forming a microfluidic assembly housing with an internal surface,
Forming a mandrel with an outer surface,
Prior to solidification of at least one of the microfluidic assembly housing or the mandrel, at least one partially solidified extending from either the inner surface of the microfluidic assembly housing or the outer surface of the mandrel. At least a portion of the outer surface of the mandrel is at least the inner surface of the microfluidic assembly housing so that the protrusion abuts on either the outer surface of the mandrel or the inner surface of the microfluidic assembly housing. Positioning the mandrel adjacent to the microfluidic assembly housing so that it is parallel to a portion,
The at least one partially solidified protrusion was deformed with respect to either the outer surface of the mandrel or the inner surface of the microfluidic assembly housing and sealed impermeable with the desired fluid flow rate. By forming a fluid channel, the impermeablely sealed fluid channel has a channel inlet and a channel outlet.
After deforming the at least one partially solidified protrusion, at least one of the mandrel or the microfluidic assembly housing and the at least one partially solidified protrusion extending from it. Sealing methods, including solidifying parts. Forming a strut with an assembly fluid outlet and
The internal surface of the microfluidic assembly housing such that the assembly fluid outlet of the strut is in fluid communication with the channel outlet prior to solidification of at least one of the microfluidic assembly housing, the mandrel, or the strut. The sealing method according to claim 2 , further comprising pressing the strut against the mandrel adjacent to the mandrel. The sealing method according to claim 3 , wherein the strut is pressed against the mandrel adjacent to the inner surface of the microfluidic assembly housing by using a motor type linear actuator. Forming a connector with an opening extending through it,
The sealing method of claim 3 , further comprising fixing the connector to the microfluidic assembly housing so that at least a portion of the column is located within the opening of the connector. Applying an adhesive to a portion of the internal surface of the microfluidic assembly housing between the internal surface of the microfluidic assembly housing and the stanchion.
Monitoring the air flow rate of the pressurized gas and
Passing the pressurized gas from the channel inlet to the channel outlet through the impermeablely sealed fluid channel.
Adjusting the pressure contact of the strut to the mandrel based on the monitored air flow rate.
The sealing method according to claim 3 , further comprising curing the adhesive when the monitored air flow rate reaches a target air flow rate. The seal according to claim 2 , wherein at least a portion of the outer surface of the mandrel has a conical shape and the impermeablely sealed fluid channel extends onto the outer surface of the mandrel in a spiral pattern. Method.

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